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UNrraD STATES PATENT OFFICE.

EDWARD R. ANDREWVS, OF NEW YORK, N. Y.

COMPOSITION FOR PRESERVING WOOD.

SPECIFICATION forming part of Letters Patent No. 247,234, dated September 20, 1881.

Application filed February 28, 1881. (No specimens.)

To all whom it may concern Be it known that I, EDWARD R. ANDREWS, a citizen of the United States, residing at the city of New York, in the county of New York and State of New York, have invented a new and useful Improvement in Compositions for Preserving Wood, hereinafter particularly set forth, of which the following is a full, clear, and exact description.

The nature of my invention relates to that class of improvements known 'as a composition for preserving substances by means of substances and materials newly made and used and properly applied for such purposes, and is connected particularly with oils, tars, and dist-illations of the same compounded, prepared, and used in the preservation of wood.

Wood rapidly decays when exposed to alternate dryness and moisture, or in damp and badly-ventilated places. The Teredo mwalis and other wood-ravaging marine-animal life destroysitwhenexposedinthesca. Hencerailway-ties and timber used in the construction of docks and bridges must often be renewed, all at great cost. Hitherto the means of preventing this loss have been in preserving the wood from decay and from attack by the use of various substances. I am aware that petroleum has been thus used 5 also, creosote or dead oil-a residuum of coal-tar left after the manufacture of gas for commercial and illuminating purposes. Such dead-oil contains chemical substances known as tar-alcohols, aterm used to embrace carbolic, cresilic, and other antiseptic acidscontained in dead-oil and sometimes called phenols, otherwise called cresols and creosote, which several acids (tar-alcohols) are never found in petroleum or in any of its products. These tar-alcohols are powerful antiseptics and exert a difl'erent effect upon the fermentable substances in wood from any substances contained in petroleum. These preservative substances have been applied by means of mechanisms and processes for substituting them in place of the native sap and moisture of the wood. In all cases where tar-alcohols have been employed in efifecting such preservation they have been employed only in the oils containing the same in natural distillation or original constitution; but such oils originally containing tar-alcohols or creosote, and

also petroleum, crude or refined, as used in wood preservation, have proved to be too expensive for such uses, so that such wood preservation, however desirable, cannot now be advantageously, largely, and profitably carried on.

I have concluded that the oils containingtaralcohols are effective in two ways in preserving \vood-viz., chemically, in causing a coagulation of the albumen in the wood, and, mechanically, in closin g the pores of the wood.

My invention consists in the composition for preserving wood, consisting of still-bottoms-a cheap substance and neverbefore used in wood preser vation-to effect the mechanical result, and dead-oil, preferably containing taralcohols in very much less quantities than hitherto required and used in wood preservation, to efiect the chemical result. v By still-bottoms is meant the residuum from the distillation of crude petroleum, constituting about seven per cent. of the crude petroleum. It is a brownish, thick, gummy substance, with a specific gravity varying from .9589 to .9150, as there is care used in distillation and the wants of commerce require. It is quite limpid at 70 Fahrenheit; but in wood preservation it is preferably used at 100 or 120 Fahrenheit. The length of time required to impregnate wood with the same varies according as the wood is porous or dry, and according to the amount of tar-alcohols used and their quality. One-half hour is often sufficient. It is far less inflammable than crude petroleum and will not flash at less than 400 Fahrenheit. It contains all the substances, in a condensed form, found in crude petroleum, valuable for wood preservation. Its greater specific gravity renders it less liable than crude petroleum to be volatilized or to be washed out of wood exposed to moisture. Its cost is much less than that of any wood preservative hitherto used, and it can be bought at two cents or less per gallon, in the largest quantities, in all parts of the country, while the dead-oil of coal-tar, which is admitted to be the most effective wood preservative hitherto used, costs from six to twelve cents per gallon, and very little can be had at any price away from the seaboard.

I have found that oils containing tar-alcohols have only about five per cent. or six per cent. of such alcohols; and my invention consists in combining one part of dead-oil (containing not less than four per cent. of tar-alcohols) with three parts of stillbottoms. This mixture would contain at least one per cent. of very powerful antiseptic substances, which is quite sufficient to arrest and prevent the fermentation of the albumen in the wood. The admixture of still-bottoms with dead-oil is even more valuable than dead-oil alone, because, being less soluble and less volatile than dead-oil, the still-bottoms preserve from evaporation the tar-alcohols, naphthaline, and other substances valuable in wood preservation contained in such dead-oil of coal-tar. Still-bottoms, moreover, possess valuable wood-preservative substances-paraffiue,ibrinstance-inlarge quantitles.

The percentages given above are found, in practical use, to accomplish the best results in preserving most of the timber and wood now used; but for use in tropical climates a larger proportion of tar-alcohols may be required. When timber has been thoroughly desiccated it contains very little active principle of fermentation and requires less of the substances of an antiseptic character, but is secured from decay by the mechanical means afforded by the fatty character of the still-bottoms alone.

Method 0ftreatment.-Every superficial treatment of timber is ineffectual. This substance should be injected into the pores of the wood. 1f the wood be very porous this can be effected by soaking the timber (if dry) in a vat containing the substance; but in most cases the wood to be preserved should be inclosed in a hermetically-sealed vessel in which has been arranged a system of steam-pipes, and which has also connected with it a vacuum-pump and aforce-pump, all of which are connected with a boiler. The wood is first subjected to the action of steam -heat to vaporize the sap and moisture in its pores. When this has been done sufficiently the moisture and air in the vessel and in the pores of the wood are pumped out by the vacuum-pum p. Then the valves are opened, which connect the vessel containing the wood with another vessel containing the preserving substance. The vacuum will draw into the treating-vessel the preserving substance, which has been previously heated sufficiently to render it limpid. When the vessel isfull a pressure is brought to bear upon the wood by means of the pressure-pump, and continued until the wood has absorbed the requisite quantity ofpreservin g material, as set forth in this specification. This wood has thus been made air-proof and water-proof, and as wood cannot decay without their presence, and also the presence of heat, the wood thus treated has been rendered imperishable from decay.

Having thus described my said invent-ion, what 1 claim, and desire to secure by Letters Patent, is-

The composition for preserving wood, which consists ofstill-bottoms combined with the dead or creosote oil derived from the distillation of coal-tar and containing tar-alcohols, as above defined, and in the above-named proportions to be applied to wood in any way for efl'ecting such preservation, all as above substantially named and described.

EDWARD R. ANDREWS.

Witnesses:

CHAS. N. SAGE, EDWD. M. ATKINSON. 

